DE2032259A1 - Variable rigidity rotor - Google Patents

Description

DR. PHIL. G. NICKEL ■ DR.-ING. J. DORNER

8 MDNCHEiI 15 LANDWEHRSTR. 85 POST BOX 104

TEL. (0811) 555719

Munich, June 30, 1970 Attorney's reference number: 14 - Pat. 58

United Aircraft Corp., 4OO Main Street, East Hartford, Connecticut O6IO8, United States of America

Variable rigidity rotor

The invention relates to rotors in which the rotor blades have a joint or other pivot connection the rotor hub and wherein a variable stiffness spring is provided between the hub and the blades is. This spring can be between a first position, in which the rotor has the properties of a rigid rotor and moved to a second position in which the rotor has the characteristics of a non-rigid rotor, and in addition, the spring can assume intermediate positions.

Rotor designs with hinged blades are described in US Patents 2,815,821 and 2,418,030, while rigid rotors are shown in US Patents 3,106,964 and λ 2,653,670. Rotor designs are also known in which springs are used to connect the blades to the hub, which also results in a non-rigid rotor, such as is described in US Pat. No. 2,949,967. These rotors behave in a similar way to rotors with hinged blades and the stiffness of the springs cannot be changed.

It is common to use either a rigid or a non-rigid rotor and the type of rotor is chosen so that that the best effect can be expected under the main operating conditions; But then you have to reduce the Accept the performance of the selected rotor under less frequent operating conditions.

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Experience has shown that a Rigid rotor and a non-rigid rotor is required that a rotor has a better performance when it is used as a rigid rotor under certain operating conditions and under other operating conditions ai non-rigid rotor acts,

It is therefore very desirable to construct a Rtor, which can be used both as a rigid rotor and as a non-rigid rotor.

Understand the rotors in transformation planes, which between a helicopter position and a propeller position movable is in helicopter position and during transition in the propeller position a non-rigid rotor desired to avoid blade root moments wShrerid the transition, as well as various load conditions to prevent. In the propeller position, the air flow is axial and therefore a rigid rotor is more suitable.

There is also even for pure Hubschraberrotoren special flight conditions where the rigid rotors non-rigid rotors are superior and umqokehrt .. Thus, "B _ffl rigid rotors Steuermomenta can develop without the large swivel angle ύ needing & χ sheet Spitz level. As is the case with non-rigid wheels. As a result, the required distance between the ector and the hull is reduced. On the composite helicopter "a rigid rotor can generate steering torque, although it only carries a small percentage of the flight weight". This does not apply to rigid rotors, which always have to develop a lift to generate ωα steering torque.

Furthermore, in pure helicopter rotors, a non-rigid rotor is a rigid rotor during forward flight, where the flapping motion of the blades is used to reduce blazing-root moments

In other rotors, such as flow pumps, turbine and compressor rotors, etc. can also be used in different operating conditions a ^ s single rotor of a sLarre version or a does not require rigid execution and thus the Lshre This invention can also be applied to such rotors,

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The object of the present invention is therefore to create a rotor - both as a rigid rotor and also can serve as a non-rigid rotor.

In accordance with the invention, this is achieved by that in an eotor with hinged blades one A variable stiffness spring is provided between the blades and the hub, the spring extending through the articulation extends and is adjustable to adjust the stiffness of the spring and therefore to change the rotor. .

Are the spring variable-rigidity consists of a package with a plurality of fins, 'for example, of spring steel, and the disk pack may comprise a first position taking wherein the slats of a deflection a maximum resistance entge- (gens tellen, further, the disk set one second position in which the lamellas offer minimal resistance to deflection and intermediate positions are also possible in which any desired stiffness value between the two extreme values can be obtained Position can be precisely influenced.

The cross section of Lamellenppketes can, for example square, rectangular, cicÜBckig, oval or circular and the cross section can be selected without the spring properties to * reduce, and "n" I adapt to the shape of the adjacent rotor head components and ausserdemkann the shape of the spring by other aspects to be determined by a specialist in the field of rotor construction? are known. ·

According to the invention, the rigidity of the rotor can be changed and can thereby be used in the most varied of conditions be adapted to the rotor drive, e.g. it is known that a very rigid rotor can generate resonance vibrations, in this case r> an, that is, according to the present invention, the rigidity of the rotor "reduce and thereby reduce the vibrations, Aul" another way can e.g. with a non-rigid rofcr, if this

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During the hover, insufficient control torque is generated, the stiffness of the spring is increased, thereby to improve the controllability of the aircraft.

According to a preferred feature of the invention, there are layers of a low coefficient of friction material such as Teflon between the Lameita of the plate pack provided.

It is possible to increase the stiffness of all blades of the rotor at the same time and to the same extent to change or to change the stiffness of each one To change the sheet separately in any desired mass.

All lamellas of the lamella set are preferably in the middle held together by a screw connection.

Another area of application of the variable stiffness spring can be seen in the fact that this spring can be used when designing a new rotor to achieve the optimal stiffness of the Determine the rotor in its final design.

The stiffness of the rotor can be changed during flight and the leaf flutter movement - can be reduced by the spring.

According to a further preferred feature of the invention is the spring with variable stiffness installed in such a way that they do not have any Transfers centrifugal loads,, ·· .-? .. * · .. ·

An exemplary embodiment of the invention is shown in the drawings, and is described in more detail below. Show it:

Figure 1 is a side view of a transformation aircraft during the Hubsehraiberbetriebc with a rotor according to the invention.

FIG. 2 shows a view of the transformation of the aircraft according to FIG. X, in the propeller operation.

Figr 3 is a plan view of a rotor, in cl & m a spring with variable Stiffness passes through the flapping hinge of a non-rigid rotor.

FIG. 4 shows a side view of the rotor according to FIG. 3,

FIG. 5 shows a section along the line S-L 'according to FIG.

Figure 6 is a view of the lamella or spring assembly after the *

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finding.

FIG. 7 shows a section through a spring assembly with a modified one Cross-sectional shape.

Figure 8 is a side view of a motor connected to the spring is to adjust the same in a 90 ° angle range.

Figure 9 is a view of a drive device to the position of several spring packages at the same time and to the same extent change.

FIG. 10 is a sectional view; of the spring assembly in the position 'with maximum rigidity.

Figure 11 is a view of the spring assembly in the position of minimum stiffness.

Figure 12 is a section through exe individual lamella of the Figure IO is in the position with maximum rigidity. ·,

FIG. 13 shows a section through a single lamella from FIG. 11 in the position with minimal stiffness,

Figure 14 is a top plan view of the variable stiffness spring jn.a semi-rigid rotor. '

Figure 15 is a side view of the variable stiffness spring according to Figure 14.

In the figures 1 and 2 a transformation aircraft 10 is shown, which grasps a fuselage 12 / which is carried by a tripod chassis, 14, 16. Wing 18 and 20 arch to opposite sides laterally from the fuselage 12 and the tail section 22 is attached to the end of the fuselage. Pivoting rotors 24 and 26 are attached to the tips of the wings 18 and 20 and are in the position for the Hubsehrafcarbetrieb in FIG Axis 34 rotates. The rotors 24 and can be given away about axes 39 and 41 and can be brought from the position according to Figure 1 for helicopter operation to the position according to Figux 2 for the Propellorbetr.leD or vice versa * In the position according to Flour 2 for the propeller leg -

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ORIGINAL-

drive rotates the rotor 26 around the axis 38 and the rotor 24 around the Axis 40. The rotors 24 and 26 are driven by one or more engines 42 and 44 powered and the thrusters are with the rotor ~ shafts connected via a conventional drive connection 46.

The engines 42 and 44 can, for example, according to the embodiments U.S. Patents 2,711,631 and 2,747,367, and the Rotors 24 and 26 can be of the U.S. Patents No. 2,984,306 and 3,080,927.

It is emphasized that although the invention with reference to a pivotable rotor describes AES Hubschrauberrotar and can djaien as an aircraft propeller, an application of the Erfindtmg in a deer Hubschraiberrotor or a pure propeller, or any other rotor is possible in which the sheets are connected to the property. The convertible aircraft 10 with pivotable rotors was selected for the description of the invention ^1, there is a rotor requires minimal rigidity during the Hubsclxauberbetrieb and a rotor is preferably with maximum rigidity during the Propellarbetrieb "

The invention is illustrated in more detail in FIGS. 3-5 and it is emphasized that the eotor 26 corresponds to the rotor 24; The rotor 24 includes a © Eofeornabe 50 die ^; "Rotates in the usual manner about axis 30 and is attached to the end of the rotor drive shaft 54, which is carried by the hull 12. The rotor 24 comprises a number of circumferentially evenly distributed Arae 56, 58 and 60 and in each arm are aligned drilling jigs 62 and 64 provided.

A number of blades 28 extend from the hub 50 and rotate with the same about the axis 30 " the angle of attack.""" Of the blades. In relation to the rotor hub, the blades can be changed from the axis 68 by rotating the blades. The blade root end 72 is supported in the blade sleeve 70 by bearings 57. The other end of the sleeve 70 grasps at a distance standing portions 74 _f 67, 76 -and 69 which is provided with flisetitenden openings 78, 80, 73 and 71 sindj which with d @ n openings 62 and are aligned in the arms 60 64 and konseiateisch to Blade flapping axis 82 lie. The flapping hinge 61 is hostile to the

Blade rack 70 pivotable with the hub 50. The cylindrical flapping hinge 84 extends through aligned openings 62, 64, 71, 73, 78 and 80 to pivot about the leaf sleeve 70 of the saddle 20 to be connected to the hub 50 around the impact axis 82 »Preferably are suitable storage facilities, such as dry storage facilities 86 and 88 between the Openings 62 and 64 and the sockets 90 and 92 are provided, which are arranged on the outside of the cylindrical flapping hinge 84. That The cylindrical flapping joint 84 is divided into two parts 84a and 84b, which are spaced along the flapping axis 82, to form void opening 94. The sleeves 84a and 84b of the flapping hinge are made by the interaction of flanges 75 and 77 with Nuts 69 and 81 held in place.

From this it can be seen that the centrifugal loading of the blade 23 in the hunter 57 is transferred and from there via the sleeve 70 and then is passed through the flapping hinge 61 to the rotor hub 50. Blade angle adjustment horn 98 is in the usual manner with the blade connected and operated by a swashplate not provided, to rotate the blade 28 about the axis 68 with respect to the sleeve 70 and the hub SO, whereby the angle of attack of the blades is either is changed jointly or periodically. Although in the From the guide shape according to Figures 3 and 4, the sleeve 70 is provided is to the leaf root end 72 with the cable 50 Euverbiriden) can the sheet with the elimination of the sleeve directly to the flapping hinge 61 can be connected if no change in the angle of attack is desired. ^ a is also possible, sheet 66 immediately | bar to be connected to the hub 50 as shown in FIG. The leaf sleeve 70 is considered to be part of the leaf 28, but This is only the case if changes to the angle of attack are desired Are. .

In Figures 3 to 4, a rotor is hingedly connected Scroll shown, the leaf with the sleeve in relation to the Got SO and the flapping hinge 61 is pivotable. If a soft one Spring is used between the hub 50 and the blade 28 can the leaf perform the ch3ag movements in an unrestricted manner and has the properties of a non-rigid rotor. However, if there is a spring between the hub 50 and the blade

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28 is provided .the flapping movement is opposed to a very strong resistance and thus the rotor 24 has the properties dines rigid rotor. It is therefore an important feature of the ■ finding that a spring 100 with variable stiffness between the hub 50 and the blade 28 is provided. Building this The spring is described below.

The variable stiffness spring 100 includes a number of lamellae 102 which may be made of metal or some other material, for example. The lamellae are stacked one on top of the other in the form of a package to form a spring or lamella package 104. As best shown in FIG. 6, the spring assembly 104 preferably comprises stacked ketallic lamellae such as 102 and 106 alternating with layers 108 and 110 of a material with a low coefficient of friction such as Teflon. Preferably, a connecting member such as a bolt 112 extends through a hole in the lamella pack 104 to hold the individual lamellae together 116 of the Lamel lenpaketes 104 are freely movable in the longitudinal direction with respect to one another, ie the lamellae must be displaceable with respect to one another in the direction of the blade angle axis 68. It is also important that the individual slats are at ... opposite ends 114 and 116 of the. Spring assembly 104 does not move laterally with respect to each other, ie in a direction perpendicular to the plane of the impact axis 82 and the blade axis 68 fells the lamellas are in the position shown in Figure 3 with maximum rigidity. In order to allow the individual lamellae to be pushed in the direction of the blade axis 60 at the end 114 of the spring 100, a fixed cylindrical member 118 is provided in the hub 50. This member 118 can either form part of the hub or it can be connected to the hub. The cylindrical member 118 receives an inner cylindrical sleeve 120 which can be rotated concentrically in the member 118 about the blade axis 68 _c

Between the fixed cylinder 118 and the rotatable cylinder 120 are, conventional dry storage 122 and 124 attached. As from fi

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Copy

BATH ORIGINAL

As can be seen in FIG. 5, the rotatable cylinder 120 has a rectangular opening 126 which receives the end 114 of the spring assembly 104 with enough play to allow the longitudinal movement (perpendicular to the plane of FIG to prevent lateral movements (to the left or to the right in Figure 5) between the slats. Although the spring assembly 104 according to FIGS. 3 to 5 has a square cross-section, any other suitable cross-sectional shape, such as, for example, rectangular, oval, circular or polygonal, can also be used, as shown in FIG. The opposite end 116 of the spring assembly 104 protrudes into an opening 128 of a rotatable ring 130, which is mounted in the sleeve 70 and wherein dry bearings 132 and 134 are preferably attached between the cylindrical ring 130 and the sleeve 70. A movement of the ring 130 in the direction of the blade 28 is prevented by a conventional Seeger ring 136 (see FIG. 3), while a movement of this ring 130 in the direction of the axis of rotation 30 is prevented by a projection 138 on the fixed cylindrical member 118. The spring package 104 is arranged in such a way that it runs through the percussion axis 82 and is carried at one end in the hub 50, while the other end is mounted in the sleeve 70 of the blade 28, so as to form a spring when percussion movements of sheet 28 with the hoof fe. 70-um ^: the stroke axis 82. appear.

As shown in Figures 3 and 8, the rotatable cylinder has 120 a projection or a crank 140 which is operated in the usual way in an angular range of 90 ° to the spring assembly 104 from the stiffer. Position according to Figures 3 to 5 in a 90 to bring a distant position, which is an articulated a leaf with a soft nib. Eteder-type actuator is shown in Fig. 8 with the rod 142 rotatably connected to the crank 140 and: I by the pilot through the hydraulic Piston-cylinder motor or the electric motor 144 is operated.

• In many fields of application it is desirable that the stiffness. of all blades of a rotor is the same u " ^r i is changed to the same extent and v / ie is shown in Figure 9 are the different-Fe-

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derpakete 104 via individual levers 142 with a star-shaped part 146 connected, which nevertheless moves the actuator 144 along the axis 30 is moved.

Öbschon in Figures 3 to 5, the spring 104 with variable Stiffness is essentially equal distances at opposite ends Sides of the impact axis 82 and the blade axis 68 extends

few and with, their haptic axis perpendicular to the first axis and parallel is to the gwaacen axis, this position of the spring 100 is not absolutely required '

To increase the operation of the spring 100 with variable stiffness explain, reference is now made to FIGS. 10-13. In the Figures 10 and 12 is the spring package 104 and a single LameDe 102 in the position with maximum stiffness, shown and this Position corresponds to a rigid rotor. In FIGS. 11 and 13, the spring assembly 104 and a single lamella 102 are in position Shown with minimal stiffness - the 90 ° from the position with Figures 10 and 12 is removed, and this position corresponds a non-rigid rotor.

The moment of inertia I of a rectangular sipe is determined by the following equation. I = ~ bh where I is the moment of inertia of the Slat, b is the width of the slat and h is the height of the slat.

It can be seen from FIGS. 12 and 13 that the base "b ^{M of} the lamella in FIG. 12 is very small, while the height ^M h ^{M of} the lamella is very large and thus a very large moment of inertia I" is obtained. that in FIG. 13 the base "b" of the lamella is very large, while the height ¹¹ Ii "is very small, so that a relatively small moment of inertia" I _x "is obtained. For example, a spring package with 88 lamellae which are 1 cm thick and approximately 10 cm long has a moment of inertia I _x = 820 cm ⁴ in the position with maximum rigidity (Figures 10 and 2) and with minimal rigidity in the position (Figures 11 and 13) in moment of inertia I _x = ^{0.08 cm 4} ". The ratio of these moments of inertia of the spring assembly 104 in the position with maximum rigidity (FIGS. 10 and 12) and in the position with minimum rigidity (FIGS. 11 and 13) is thus 10,300 to 1.

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In other words, the spring assembly 104 is in the position according to FIG. 10 is 300 times more rigid than in the position according to FIG. 11. Thus, a bending force is that in the spring 104 in the position according to Figure 11 causes a deflection of 2.5 cm in the spring 104 in the position according to FIG. 10 only a deflection of 0.00025 cause cm «.

When the spring pack 104 is brought into positions which between 10 and 11, the stiffness of the spring changes with each new setting, so that the spring 100 has a variable stiffness, which not only has a maximum value as in FIG. 10 and a minimum value as in FIG. 11 can take, but it can also take any of these both end values. Stiffness can be adjusted.

Using this spring with variable stiffness results in a non-rigid rotor when the spring is in position with minimum stiffness and a rigid rotor when the vein is in is the position with maximum stiffness and the pilot of a helicopter in which the spring with variable stiffness is installed, can for the respective operating conditions Select either rigid rotor operation or non-rigid rotor operation. The spring with variable stiffness can be used to reduce the stiffness of a rigid rotor when resonance vibrations become noticeable. The variable stiffness spring can be used as an experimental or dimer ionization aid Apply when developing a new | Rotor design the most suitable stiffness for optimal rotor performance should be determined.

While in the explanation of the invention, a rotor is described who only understands a flapping hinge, it is also mentioned that the invention can also be used in a rotor that only has a Pivot joint or a pivot joint and a flapping joint, in which case a spring with variable stiffness in each joint is built in. '

In addition, the spring with variable stiffness can also be used in roteren are used that do not have a Galenk, but the

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Blades are shaped accordingly to give the rotor's properties of a non-rigid rotor.

In Figures 14 and 15, the variable stiffness spring 100 is used in a semi-rigid rotor 120 ¹ which has a hub 50 'which rotates about axis 30' and a number of blades 28 * extending from hub 50 ' to revolve around the same and are held in bearings 57 in order to be able to carry out a change in the angle of attack. The blades 28 'have a flexible region 150 in which the blade 28' can flex with respect to the hub. In such a Rotabauwej se the spring with variable stiffness, which has the same structure as in FIGS. 2-5, is arranged above the blade 28 'and is supported in bearings 152 and 154 so that it can be used by the pilot via a rod 160 . Ring 158 and rod 156 can be rotated. The spring 100 could of course also be installed between the hub 50 and the bearing 154 on the blade 28 *.

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Claims (17)

"B" egexem - ;: i $ .T: - 13 - May not be changed] PATE KTA NSP R Ü C HE 2032259 1. kotor with a hub rotatable about an axis, a number Blotters, which streak from the hub and circulate with it, each sheet having a bendable area or about ' a hinge is attached to the hat, so that the leaf is in Can move with respect to the hub, characterized in that a Spring with variable stiffness is arranged in the flexible area or between the hub and the blade in the hinge. 2. "Rotor according to claim 1, characterized in that the spring with variable stiffness a number of lamellas selected Dimensions-owns, with the slats stacked on top of each other are to form a spring package in which the ends of the individual Slats are movable relative to one another in the longitudinal direction. 3. Rotor according to claim 2, characterized in that the lamellae Metal slats are of selected width and height. 4. Rotor according to claim 2, characterized in that one layer consists of a material with a low coefficient of friction in the spring assembly with the Alternating slats. 5. Rotor according to one of claims 1 to 4, characterized in that that means are provided to the individual lamellae of the spring assembly to connect with each other. 6. Rotor according to one of claims 2 to 5, characterized in that « that all slats have the same rectangular shape and a rectangular f have kigen cross-section to form a rectangular spring package. 7. Rotor according to one of claims 2 to 5, characterized in that that the spring package has a non-rectangular cross-section, 8. Rotor according to one of claims 1 to 7, characterized in that the ends of the spring with variable stiffness lie on opposite sides of the axis äea joint. 9. Rotor according to one of claims 1 to 8, characterized in that the OeletVic is a flapping hinge. 10 * rotor according to claim 2, characterized in that actuation ** - Means are provided to urn the spring package between a first 10 988 3 / Θ0 & 1- ■■ ■: Position in which each lamella has a cross-section with maximum rigidity and to a second location, wherein each lamella has a cross-section with minimal stiffness. 11. Rotor according to claim 10, characterized in that in the first position each lamella has a cross-section of greater height as width and that in the second position each lamella has a cross section with greater width than height. 12. Rotor according to Anspnrh IO or 11, characterized in that each Lamella has the same cross-sectional shape and that the spring assembly includes a selected number of lamellae around a spring to form variable stiffness in the first and the second position. 13. Rotor according to claim IO or 11, characterized in that the individual lamelin have a different cross-section to a To form spring with the desired stiffness in the first position and in the second position. 14. Rotor according to claim 11, characterized in that each Blade of a rotor has the same spring with variable stiffness • and the means are provided to increase the stiffness of the springs simultaneously in the same direction and. in the same. To change mass. 15. Rotor according to claim 2, characterized in that one end the spring package in the property is so gäagort: is that the individual Slats can move lengthways relative to each other, while a movement in the lateral direction of the individual slats is prevented in relation to one another, and that the other end of the spring assembly is mounted in the leaf in such a way that the individual Slats siah can move lengthways in relation to each other, while a lateral movement of the individual slats in relation to ciuf- " each other is prevented., 16. Rotor according to claim 15, characterized in that the spring is mounted with variable rigidity in the hub and in the blade that no centrifugal loading is introduced into the spring will.. . 10988370091 ■ -. ■ BAD ORaGISSiAL - 17. Rotor according to one of the ιοίgoing claims, characterized in that that the spring is built into a helicopter rotor. 109863/0091